The once cordial stars are now seemingly deadlocked at the judges’ table. So where did all the fighting begin?

Minaj’s profanity-laced outburst (which was caught on video and posted on TMZ) may have been the final straw in a series of difficulties between the stars.

“Mariah has been saying little things to jab at Nicki from day one of shooting,” an Idol source tells PEOPLE. “Mariah doesn’t think Nicki can sing and doesn’t think she should be judging folks. Nicki has been taking all of the jabs, but on this particular day she lost it.”

Other insiders insist Carey did not provoke Minaj. But clearly tensions were high, as Minaj had stormed off the set earlier in the day.

“There was a contestant who liked opera, and Mariah was talking to her as a pop singer who also liked opera,” says one insider. “Nicki cut her off and slammed her fist on the table. Mariah may have been going on a bit too long but she did apologize. But then Nicki flipped out and started yelling.”

A Threat Against Mariah?

After the outburst, according to multiple sources who were there (as well as Carey herself, whom Barbara Walters quoted on The View the next day), Minaj said as she was walking off the set, “If I had a a gun I’d shoot that f—ing b-tch.” (Idol producer Nigel Lythgoe on Wednesday said the report was “absolutely not true.”)

On Thursday, Minaj Tweeted, presumably in reference to Carey: “All I do is compliment u. That’s not enuff? Ur a legend, cheer up. U don’t have to run down ur resume or feel intimidated. Shady McGrady…”

As for who leaked the damning video, “On the day of the fight production staff were the only people in the room,” says the Idol source. Now that the catfight is out of the bag, “they are talking about firing Nicki. That is still up for debate. They are worried about how she will act during the live shows.”

On Friday, American Idol producers issued a statement:

“This is one of the best, most passionate, dynamic and invested judging panels we’ve ever had. We love and support all of the judges and the fantastic work they are doing, and we can’t imagine a better group to find the next American Idol. Despite all the accusations and media speculation – much of which is inaccurate – production is going extremely well today and the judges are focused on finding the best talent here in Baton Rouge.”

A source close to Minaj told PEOPLE earlier this week that the rapper has “always been really professional. She’s like a Gaga or Madonna and is very serious about the order of things. She is tough and direct minded.”

But is she prone to violence?

Minaj Tweeted about the incident, speaking in the the third person and referring to Walters’s commentary: “Hey yAll. Lets just say nicki said smthn about a gun. ppl will believe it cuz she’s a black rapper. Lmao. I’ll then hit up Barbara n milk it.”

Insiders tell PEOPLE that Carey has hired extra security in the wake of the threat. Still, says one, “Mariah knows she has a job to do and doing it. She is a professional and the show goes on.”

As of late Thursday, the feuding judges were back to being professionals. For now, at least.

“There was a photo shoot [Thursday] with all the judges and Ryan [Seacrest], and everybody showed up and it went smoothly,” a source close to production tells PEOPLE. “Everyone is looking forward to another full day of judging in Baton Rouge on Friday – and to moving forward.”